The alert for Molecular Phylogenetics and Evolution came in today, and I was
reminded of 2 others in Journal of Zoological Systematics and Evolutionary.
Research.
GBR.
Bleidorn, C.; Vogt, L. ; Bartolomaeus, T. 2003: A contribution to sedentary
polychaete phylogeny using 18S rRNA sequence data. Journal of Zoological
Systematics and Evolutionary Research 41: 186-195.
Abstract: Abstract The phylogenetic position of Annelida as well as its
ingroup relationships are a matter of ongoing debate. A molecular phylogenetic
study of sedentary polychaete relationships was conducted based on 70
sequences of 18S rRNA, including unpublished sequences of 18 polychaete
species. The data set was analysed with maximum parsimony and maximum
likelihood methods. Clade robustness was estimated by parsimony-bootstrapping
and jackknifing, decay index, and clade support, as well as a posteriori
probability tests using Bayesian inference. Irrespective of the applied
method, some traditional sedentary polychaete taxa, such as Cirratulidae,
Opheliidae, Orbiniidae, Siboglinidae and Spionidae, were recovered by our
phylogenetic reconstruction. A close relationship between Orbiniidae and
Questa received a particularly strong support. Echiura appears to be a
polychaete ingroup taxon which is closely related to Dasybranchus
(Capitellidae). As in previous molecular analyses, no support was found for
the monophyly of Annelida nor for that of Polychaeta. However, we suggest that
an increase in taxon sampling may yield additional resolution in the
reconstruction of polychaete ingroup phylogeny, although the difficulties in
reconstructing the basal phylogenetic relationships within Annelida may be due
to their rapid radiation.
Pleijel, F. ; Rouse, G. W. 2003: Ceci n'est pas une pipe: names, clades and
phylogenetic nomenclature. Journal of Zoological Systematics and Evolutionary
Research 41: 162-174.
Abstract: An introduction is provided to the literature and to issues
relating to phylogenetic nomenclature and the PhyloCode, together with a
critique of the current Linnaean system of nomenclature. The Linnaean
nomenclature fixes taxon names with types, and associates the names with ranks
(genus, family, etc.). In phylogenetic nomenclature, names are instead defined
with reference to cladistic relationships, and the names are not associated
with ranks. We argue that taxon names under the Linnaean system are unclear in
meaning and provide unstable group-name associations, notwithstanding whether
or not there are agreements on relationships. Furthermore, the Linnaean rank
assignments lack justification and invite unwarranted comparisons across taxa.
On the contrary, the intention of taxon names in phylogenetic nomenclature is
clear and stable, and the application of the names will be unambiguous under
any given cladistic hypothesis. The extension of the names reflects current
knowledge of relationships, and will shift as new hypotheses are forwarded.
The extension of phylogenetic names is, therefore, clear but is associated to
(and thus dependent upon) cladistic hypotheses. Stability in content can be
maximized with carefully formulated name definitions. A phylogenetic
nomenclature will shift the focus from discussions of taxon names towards the
understanding of relationships. Also, we contend that species should not be
recognized as taxonomic units. The term 'species' is ambiguous, it mixes
several distinct classes of entities, and there is a large gap between most of
the actual concepts and the evidence available to identify the entities.
Instead, we argue that only clades should be recognized. Among these, it is
useful to tag the smallest named clades, which all represent non-overlapping
groups. Such taxa - LITUs (Least Inclusive Taxonomic Units) - are
distinguished from more inclusive clades by being spelled with lower-case
initial letter. In contrast to species, LITUs are conceptually straightforward
and are, like other clades, identified by apomorphies.
Bleidorn, C.; Vogt, L. ; Bartolomaeus, T. 2003: New insights into polychaete
phylogeny (Annelida) inferred from 18S rDNA sequences. Molecular Phylogenetics
and Evolution 29(2): 279-288.
Abstract: Annelid systematics and the ingroup relationships of polychaete
annelids are matter of ongoing debates in recent analyses. For the
investigation of sedentary polychaete relationships a molecular phylogenetic
analysis was conducted based on 94 sequences of 18S rDNA, including
unpublished sequences of 13 polychaete species. The data set was analyzed with
maximum parsimony and maximum likelihood methods, as wells as Bayesian
inference. As in previous molecular analyses the monophyly of many traditional
polychaete families is confirmed. No evidence has been found for a possible
monophyly of Canalipalpata or Scolecida. In all analyses a placement of the
Echiura as a derived polychaete ingroup with a close relationship to the
Capitellidae is confirmed. The orbiniids appear paraphyletic with regard to
Questa. Travisia is transferred from Opheliidae to Scalibregmatidae. The
remaining opheliids include a yet undescribed ctenodrilid species from Elba,
whereas the other investigated ctenodrilid Ctenodrilus serratus groups with
the Cirratulidae and shows a close affinity to the cirratulid genus
Dodecaceria. A common ancestry of Branchiomaldane and Arenicola, which has
been predicted on morphological data, is confirmed by the analysis and a
sistergroup relationship between Arenicolidae and Maldanidae is also
recovered. These results support our assumption that on the basis of a broader
taxon sampling the phylogenetic position of controversially discussed taxa can
be inferred by using 18S rDNA sequence data.
Nygren, A. ; Sundberg, P. 2003: Phylogenjy and evolution of reproductive modes
in Autolytinae (Syllidae, Annelida). Molecular Phylogenetics and Evolution 29:
235-249.
Abstract: The phylogeny of 31 autolytine taxa (Syllidae, Polychaeta, and
Annelida) was estimated based on 16S rDNA and 18S rDNA sequences. Outgroups
included 12 non-autolytine syllids and four other annelids from related
groups. The phylogeny was used to trace the evolution of the various
reproductive strategies (i.e., epigamy, anterior and posterior scissiparity,
and gemmiparity) within the group, and it will also serve as a basis for a
forthcoming revision of autolytine taxonomy. The two genes were analysed both
separately and in combination using parsimony, maximum likelihood, and
Bayesian inference. Regardless of method used the combined analysis supported
a division of Autolytinae into three major clades: one with epigamous
Autolytus; a second comprising Autolytus and Myrianida with posterior
scissiparity and gemmiparity; and a third containing Proceraea, Procerastea,
and Virchowia with anterior scissiparity. The relationship between these three
groups is uncertain. Ancestral reproductive states were reconstructed with
parsimony and maximum likelihood, and the results unequivocally support
epigamy as the plesiomorphic reproductive mode in Syllidae, and that
schizogamy in Syllinae and Autolytinae are separate events. The evolution of
reproductive traits is ambiguous within Autolytinae, and either of the
different reproductive modes could represent the ancestral state.
--
Geoff Read <g.read at niwa.co.nz>
http://www.annelida.net/
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